Safety plug for explosive cartridge



a 1 MN) \l3C s/mu m/ FHW/AWUTLFQ. (m. WW. M \ni. iIW b V w Wm l0 Q1 l. mc m W W Nov. 3, 1964 w. F. BROSKE SAFETY PLUG FOR EXPLOSIVE CARTRIDGEFiled July 2, 1962 United States Patent 3,155,039 SAFETY PLUG FOREXPLGSIVE CARTGE William F. Broske, Camp Hill, Pa, assignor to All?Incorporated, Harrisburg, Pa. Filed July 2, 1962, Ser. No. 206,767 4Claims. (Cl. 102-38) In the use of powder-actuated tools for industrialpurposes, I have discovered that a plastic cartridge may be used toadvantage, especially of a construction wherein the cartridge has acentrally-located plug and the primer is disposed in the plug, asdescribed in my prior application Serial No. 793,814, filed February 17,1959, now Patent No. 3,007,409.

Upon inserting the shell into a tool, an air pocket may form in thecasing and cause the firing pin to move forward ahead of it. After theshell is inserted into the tool, it is necessary to retract the firingpin to place the tool in operative condition. While it is recommendedthat the tool operator does not use his fingers in retracting the firingpin, there is always the possibility that he will do so. If he moves thefiring pin too quickly, he may inadvertently actuate the device. This isespecially true if the firing pin sticks while it is being retracted,and the operator tries to force the pin into position.

It is an object of the invention to provide such a plastic cartridgehaving a novel plug which prevents actuation of the cartridge when thefiring pin is being retracted, but permits the cartridge to be firedafter the tool is loaded.

It is a further object of this invention to provide a series of prongson the front of the plug to protect the primer against a rearward thrustof the firing pin. However, these prongs may be disabled by rotating thecartridge relative to the firing pin, thus bending them out of positionprior to firing.

Other objects and attainments of the present invention will becomeapparent to those skilled in the art upon a reading of the followingdetailed description when taken in conjunction with the drawings inwhich there is shown and described an illustrative embodiment of theinvention; it is to be understood, however, that this embodiment is notintended to be exhaustive nor limiting of the invention but is given forpurposes of illustration in order that others skilled in the art mayfully understand the invention and the principles thereof and the mannerof applying it in practical use so that they may modify it in variousforms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIGURE 1 illustrates a perspective view (partially broken away) of aplug embodying the principles of this invention;

FIGURE 2 illustrates a tool having a cartridge containing the device ofFIGURE 1 therein, in inactive condition;

FIGURE 3 is a view similar to FIGURE 2 showing the cartridge ready forfiring;

FIGURES 4, 5 and 6 are views of the plug shown in FIGURE 1 inconjunction with a fragmentary view of the firing pin during the variousstages of loading and firing; and

FIGURE 7 is a top sectional view taken through plane 7-7 of FIGURE 5.

As shown in FIGURE 1, the plug comprises a cylindrical member 10,preferably made of polyethylene or other plastic material. One end ofthe plug 10 has a major coaxial aperture 12 adapted to receive andsupport a priming means 14. The other end of the plug has a minorcoaxial aperture 16, which permits the primer to actuate a powder chargewhen the primer is ignited. A

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series of V-shaped grooves 18- extend circumferentially around the outersurface of the plug. These grooves permit a tight engagement between theouter surface of the plug and the inner surface of the cartridge, thusacting as a gas check.

A plurality of longitudinally-extensible prongs or legs 2% project fromthe surface of the plug in which the primer is inserted. While anynumber of legs may be employed, in the preferment (FIGURE 1) four suchlegs are disposed about the primer at from each other. These legs may beof the same material as the plug and may be integral with the plug. Thelegs extend a sulficient distance to protect the primer against thefiring pin when the firing pin is driven toward the primer. However,they are so constructed so that when there is a rotary motion betweenthe firing pin and the plug (FIGURES 4 and 5), the legs will be bent outof the way quite easily and permit the firing pin to strike the primer.

To provide additional background on the use of the invention, FIGURES 2and 3 illustrate a powder-actuated, industrial tool suitable foremployng an exposive device containing a plug as set forth in FIGURE 1.FIGURE 2 shows the device after loading the shell, but prior toconverting it from its inactive to its active condition.

The tool of FIGURES 2 and 3 includes a body member B adapted to receivea C-shaped connector 30 with a central wedge 32 slidable therein tograsp a pair of conductors C and C. (This is disclosed in a priorapplication, Serial No. 172,183, filed February 9, 1962.)

One end of the body member has an internally-threaded aperture 34adapted to receive a housing 36 with external screw threads. The housing36 is secured to a sleeve 33 which retains a firing chamber 49 therein.A cap 42 is adapted to be threaded onto the free end of the housing 40.A cartridge 44 is insertable into the firing chamber, and has a head 46on one end which retains it against one end of the firing chamber. Anexplosive charge 43 is contaned in the shell, and the plug 10 (aspreviously described in FIGURE 1) is inserted into the shell with afriction-fit to retain the explosive charge therein. A flange 49 on thefiring chamber 40 abuts a setscrew 50 to permit sliding motion betweenthe sleeve 38 and the firing chamber, but permits them to traveltogether in a rotary direction. A firing pin 52 is slidable in thefiring chamber and penetrates the open end of the shell 44. The otherend of the firing pin comprises a head member 53 which projects from thehousing 36 and, when fired, bears against the wedge 32 to drive it intoposition (see FIGURE 3).

A prong 54 projects from the cap 42 to puncture the head 46 of the shell44 and permits the escape of gases when it is desired to Withdraw thecartridge.

Operation-When it is desired to connect a pair of conductors, theconnector 30, wedge 32, and conductors C and C are positioned in thebody member B. A can tridge 44 is inserted into the firing chamber 40and the cap 42 secured to the firing chamber to retain the shelltherein. The firing pin 52 is moved into its rearward position (as shownin FIGURE 2), whereby the legs 20 prevent the firing pin from beingdriven against the primer 14. An attempt to drive the firing pin towardthe primer puts the legs under compression, and thus protects the primeragainst accidental ignition.

The barrel 38 is then rotated in a clockwise direction causing thescrewthreads 34 to move the firing chamber inwardly until the head 53touches the Wedge 32. Continuing the threading operation causes the head53 to be frictionally retained against the wedge 32, and thus provides arotary motion between the firing pin 52 and the legs 20. Although thelegs 20 resist compression in a longitudinal direction, they may be bentover fairly easily in sidewise direction. As shown in FIGURE 5, they arethus deformed out of a position wherein they protect the primer, andinto a position permitting the firing pin to be driven against theprimer (see FIGURE 3).

The cap 42 may be struck a sharp blow (e.g., with a hammer or a pair ofpliers), and the cap 42 and firing chamber 40 will be drivenlongitudinally toward the housing 36, thus driving the plug against thefiring pin 52 and causing the firing pin to ignite the primer 14.Ignition of the primer 14 explodes the charge 48 and causes it to bedriven forwardly, driving the firing pin ahead of it. The forward motionof the firing pin causes it to drive the wedge 32 into the connector 30,thus making a secure electrical connection.

. Thus itiistseen that the legs 20, While having a high com- 7 pressivestrength, to protect the primer against inadvertent ignition, arerelatively flexible in a sidewise direction which permits them to befolded out of the way prior to firing the device. The design of the plug10 eliminates the human error in the use of a safety device, since theoperator is not required to set or unlock a safety mechanism, nor can hedisable it.

Changes in construction will occur to those skilled in the art andvarious apparently different modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only. The actual scope of the invention is intended tobe defined in the following claims when viewed in their properperspective against the prior art.

I claim:

1. A plug for use in an explosively-operated tool comprising: acylindrical member having a primer-receiving means in one end thereof, aprimer in said primer-receiving means, a plurality of projectionsextending from said plug and surrounding said means, said projectionshaving high compressive strength in a longitudinal direction but beingrelatively flexible in a transverse direction so that they can be bentout of the way prior to firing the cartridge.

2. A cartridge for a powder-actuated tool comprising: a cylindricalshell closed at one end, a powder charge in said shell adjacent saidclosed end, a plug in said shell for retaining the powder chargetherein, a percussion primer in said plug, said primer exposed to theopen end of the shell, and means for preventing inadvertent actuation ofsaid primer.

3. A cartridge for a powder-actuated tool comprising: a cylindricalshell closed at one end, a powder charge in said shell adjacent saidclosed end, a plug in said shell for retaining the powder chargetherein, a primer in said plug, said primer having an actuating surfaceexposed to the open end of the shell, a plurality of members projectingfrom said plug toward the open end of said shell, said members capableof resisting force applied in a longitudinal direction while capable ofbeing easily bent by a transverse force.

4. A cartridge for a powder-actuated tool comprising: a cylindricalshell closed at one end, a powder charge in said shell adjacent saidclosed end, a plug in said shell for retaining the powder chargetherein, a primer in said plug, said primer having an actuating surfaceexposed to the open end of the shell, said plug made of a plasticmaterial, a plurality of integral members projecting from said plugtoward the open end of said shell.

References Cited in the tile of this patent UNITED STATES PATENTS1,040,762 Rodrigues Oct. 8, 1912 2,345,618 McCormick Apr. 4, 19442,441,907 Schmitt' May 18, 1948 2,640,184 Bauer May 26, 1953 3,007,409Broske NOV. 7, 1961 3,009,419 Clay Nov. 21, 1961

1. A PLUG FOR USE IN AN EXPLOSIVELY-OPERATED TOOL COMPRISING: ACYLINDRICAL MEMBER HAVING A PRIMER-RECEIVING MEANS IN ONE END THEREOF, APRIMER IN SAID PRIMER-RECEIVING MEANS, A PLURALITY OF PROJECTIONSEXTENDING FROM SAID PLUG AND SURROUNDING SAID MEANS, SAID PROJECTIONSHAVING HIGH COMPRESSIVE STRENGTH IN A LONGITUDINAL DIRECTION BUT BEINGRELATIVELY FLEXIBLE IN A TRANSVERSE DIRECTION SO THAT THEY CAN BE BENTOUT OF THE WAY PRIOR TO FIRING THE CARTRIDGE.